Among electronic devices including a component (acoustic component), such as a sound emitter like a speaker or a buzzer and a sound receiver like a microphone, which is involved in acoustic function, there are many devices, as exemplified by mobile phones and digital cameras, which are carried and used outdoors. In recent years, it has been required to impart waterproof function to such electronic devices including an acoustic component while ensuring their sound transmitting properties. Waterproof mobile phones and waterproof digital cameras etc. have already become widespread, and, in order to protect acoustic parts (acoustic components) of such devices, filters having waterproof function and sound transmitting function have been used.
For example, an outer housing of a waterproof camera including a microphone and a speaker is provided with openings located at positions corresponding to those of the microphone and the speaker. The openings are covered with filters having waterproof function and sound transmitting function, so that both sound transmitting properties and waterproofness are ensured.
It has been proposed to use a microporous membrane like a stretched polytetrafluoroethylene (PTFE) film as a protective member for protecting an acoustic component (see Patent Literature 1, for example).